More than 64,000 people are in Australia illegally after overstaying work and tourist visas, with the federal government estimating as many as 12,000 have been here for more than 20 years.
New figures from the Department of Immigration and Border Protection show temporary visitor visas are the mostly likely to be abused in Australia, while Malaysian nationals made up the largest group of unlawful non-citizens in the country last financial year.
There were nearly 10,000 Malaysians recorded as having overstayed visas in 2016-17, along with about 6500 Chinese nationals and 5170 from the United States.
Countries outside the top 15 most likely to overstay represented nearly 18,000 in the category. About 3700 UK nationals overstayed, ahead of 2780 Indonesians and 2730 Indians.
A Senate committee has heard as of June 30 there was an estimated 64,600 visa overstayers in the country and of the 12,966 located last financial year, more than 1750 were found to be working without the required authorisation.
About 5000 people are believed to have overstayed for three months or less, more than 11,000 have overstayed between two and five years and 6600 between 15 and 20 years.
A further 12,080 are believed to have stayed illegally for 20 years or longer.
The department said more than 47,000 visitor visa recipients had overstayed, along with 9690 students visa holders. Bridging and migrant visas made up fewer than 700 of overstays.
Officials could not say how much was spent in attempts to locate visa overstayers in the community, but a total of $72.4 million was spent on compliance activities.
Nick Xenophon Team senator Stirling Griff used Senate estimates hearings to press officials for data about visa breaches.
Senator Griff said the department's focus for apprehension was on high-risk individuals and enable organisations, including rogue labour hire businesses.
"Given that almost 20,000 illegal overstayers have been in Australia for more than 15 years, it makes a mockery of the border protection focus on so called boat people and their lack of Australian placement," he said.
"Most of these almost 65,000 would have travelled to Australia by air and the overwhelming majority have settled into Australian life, with little – if any – regard for our laws and responsibilities.
"The department stated that it was a fair estimate that 20,000 were also working illegally. That's at least 20,000 illegal overstayers taking Australian jobs."
Senator Griff said better checks were needed to prevent temporary visitor and tourist visa recipients from overstaying in Australia.
"These are the easiest to abuse, as there is little checking up of tourists. Given that more than 47,000 overstayers came here on tourist visas and well over half originated from Asian countries, there is a good argument for a greater degree of scrutiny," he said.
The department says it generally does not detain people found to have overstayed visas if they work with officials to resolve their cases.
A resolution service gives people living or working unlawfully in Australia the chance to engage with officials to resolve their immigration status.